EMERYVILLE >> A juvenile whale who beached itself several times since it was first spotted in the San Francisco Bay last week was euthanized Tuesday after a team from the Marine Mammal Center determined that it was sick and behaving abnormally, once again beaching itself during low tide.

The whale was beached on an offshore mudflat at the McLaughlin Eastshore State Park near Emeryville, officials said.

The Marine Mammal Center’s team made the decision to humanely euthanize the whale Tuesday afternoon in consultation with the center’s lead veterinarian “to relieve this animal of its suffering,” said Giancarlo Rulli, the associate director of public relations for the Marine Mammal Center. The whale was euthanized around 3:30 p.m. after being given an anesthetic to calm it.

“This is a very difficult decision that we worked very closely in conjunction with NOAA (the National Oceanic and Atmospheric Administration) on, but it’s guided in how the animal has been behaving for the past week,” Rulli said. “It’s displaying signs that are abnormal for a whale to continue to beach itself consecutively like this over a week’s time.”

A minke whale — possibly the same species as the animal reported off Emeryville — and a gray whale were found dead this month in separate incidents along other portions of the California coast. Two other gray whales washed up in Northern California in the past week and a half, Rulli said — one near Angel Island and one at Fort Point in San Francisco. “To have four whales wash ashore in a week’s time is an absolute cause for concern,” Rulli said.

Rulli explained that the juvenile whale was behaving abnormally and “showing signs that are just not typical of a normal, healthy, thriving whale.” He added that the whale had beached itself several times since it was first sighted April 2 and was suffering from a severe sunburn from stranding itself at low tide.

“For a whale to repeatedly continue to take actions that are just kind of the antithesis of what a normal, healthy whale would normally do, that was a huge cause for concern,” Rulli said.

The sunburn had partially healed with fibrous tissue, but whales, unlike other marine animals like seals, are not meant to be exposed to sun for extended periods of time, Rulli added.

“What was very telling and significant to all of us was just how far that this individual had willed itself, through shallow water, in mud, to its eventual resting place, which was just roughly 20 feet from the beach itself,” Rulli said. “The animal’s breathing was labored and stressed, meaning much more rapid than it had been even Monday.”

The center’s pathology team conducted an on-site necropsy Tuesday to conduct an investigation into what caused the animal to continue to beach itself and whether there is a condition that cannot be determined by the naked eye, Rulli said. The necropsy, which can take weeks to months to complete certain tests, will test for infectious diseases and neurotoxins, such as domoic acid, an algal toxin that has been poisoning dolphins and sea lions off the coast of California.

There were no immediately conclusive causes of the whale’s behavior found during the necropsy, which involved collecting tissue samples from organs, blubber and more, Rulli said.

“Through a necropsy investigation, (the whale) will have another chapter to write, in terms of not only knowledge about what was going on with this specific individual whale, but potentially broader implications for understanding a species that, unlike humpback whales and gray whales, is quite elusive,” Rulli added.

Before it was euthanized, the whale was sprayed with water to keep it cool and to help relieve any suffering that came with being out of the water with its skin condition, Rulli added.

The East Bay Regional Park District and Alameda County Fire Department were also there Tuesday to try to help the animal unbeach itself, the park district said on social media.

The whale was first sighted swimming in a similar area April 2. Around 2 p.m. Monday, the whale was temporarily stuck in a mud patch in a shallow area of the bay during low tide, the center said. The whale remained calm and moved back into deeper waters on its own around 4:30 p.m. during high tide.

The center noted that on Monday the whale “swam well under its own strength with good energy, which our experts noted as a good sign.”

Experts added that the whale’s exact age, sex and estimated length are not known, but Rulli noted that the team estimated the length to be about 20 feet. The center’s Cetacean Conservation Biology Team identified the whale to likely be a juvenile minke whale based on photographic evidence. If it is confirmed to be a minke whale, it will mark the fifth confirmed sighting in the past 16 years in the San Francisco Bay.

“This is quite a rare sighting,” Rulli said.

Staff photographer Jane Tyska contributed to this report.